RFR: 8306135: Clean up and open source some AWT tests [v2]

[Alexander Zuev]

> Cleaning up and open sourcing three AWT tests

Alexander Zuev has updated the pull request incrementally with two additional commits since the last revision:

 - Cosmitic change: couple of extra-long strings were reformatted to be shorter
 - Added a line separating class declaration from imports

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13518/files
  - new: https://git.openjdk.org/jdk/pull/13518/files/70d5b596..8877ee01

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13518&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13518&range=00-01

  Stats: 5 lines in 2 files changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13518.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13518/head:pull/13518

PR: https://git.openjdk.org/jdk/pull/13518